In a conventional mobile communication system, a so-called circuit-switched radio channel for voice and TV-phone communication services and the like and a packet exchange radio channel for Internet connection service are separately provided. Because of this feature, when a voice service and an Internet connection service are being simultaneously provided, simultaneous control for setting both radio channels is being performed. One of the major reasons why the radio channels are separately provided for a circuit-switched call and a packet exchange call respectively is that the traffic characteristics occurring in services on one radio channel are largely different from those of the other. Because of this difference, by providing separate radio channels and optimizing a battery energy saving method, radio performance is desired to be improved.
However, recently and continuously, there is a demand for a so-called all-IP environment where even circuit-switched data such as voice data are divided into IP packets and transmitted as IP packets. This demand is particularly strong in wired networks. In all-IP transmission, basically, all data are divided into IP packets and a common transmission process is performed with respect to each of the IP packets. Because of this feature, a control process and implementation of the process may be easier compared with a circuit-switched system in which each of the currently transmitting service types is required to be recognized and an adequate transmission method adapted to the service is required to be selected. Further, there is a strong demand that various applications such as Web access or data transmission be provided at the same time as voice communication service. This demand also encourages the all-IP environment.
This demand is also growing in radio communication systems. In a latest method (trend), a shared channel which is a radio channel shared by all traffic is used to achieve the all-IP environment. In this method using the shared channel, it is not necessary to recognize an upper layer service in processes of generating radio frames and encoding and the like, thereby facilitating the implementation of this shared channel transmission method.
On the other hand, however, when techniques specific to mobile communications such as a battery energy saving technique are considered, performing control based on the recognition of the upper layer service may be preferable. Specifically, in voice communication, packet data are generated typically at regular intervals. Because of this feature, it is possible to previously fix receiving/transmitting timing. By doing this, it becomes possible to turn off a receiving circuit of a mobile station at the timing when the voice communication is not being performed. As a result, it becomes possible to perform an optimization process including easily saving battery power.
However, on the shared channel, when a common scheduling process is performed without recognizing service types of data to be processed, the mobile station has to be prepared to receive data in every data reception timings because the mobile station cannot predict when or in which traffic pattern data packets are being generated. As a result, even when only voice communication is being performed and the data are intermittently received, the mobile station has to be prepared to receive data at every receiving timing. As a result, this method is disadvantageous from a battery energy saving point of view, and a technique for overcoming the problem has been desired.
As prior-art documents pertaining to the present invention, there are the following Patent Documents 1 and 2.    Patent Document 1: Japanese Patent Application Publication No. 2004-289234    Patent Document 2: Japanese Patent Publication No. 2006-501721